(a) Field of the Invention
The present invention relates to an inner cylinder direct injection spark ignited internal combustion engine and, more particularly, relates to control techniques on a fuel injection timing and an ignition timing at a time of a cold start of the engine demanding an earlier temperature rise (earlier activation) of a catalytic converter of an exhaust system in the internal combustion engine.
(b) Description of the Related Art
A Japanese Patent No. 3325230 issued on Jul. 5, 2002 (which corresponds to a U.S. Pat. No. 6,345,499 issued on Feb. 12, 2002) describes a previously proposed technique in which, as a catalyst warming up method of the inner cylinder (in-cylinder) direct injection stark ignited internal combustion engine, at least twice (two times) split injections are carried out which include: a later period injection to form an air mixture fuel having a partial rich and lean air-fuel ratio within a combustion chamber within an interval of time from a suction stroke to an ignition timing; and an earlier period injection in which fuel is injected at a timing before the later period injection to enable a spreading of fire with a fuel at the later period injection and with a combustion at the later period injection to generate the air mixture fuel of a leaner air-fuel ratio than a stoichiometric air-fuel ratio, when an exhaust gas purification purpose catalytic converter is in an un-warmed up state in which a catalytic converter temperature is lower than an activation temperature of the catalytic converter, the ignition timing is retarded by a predetermined quantity toward a more retardation angle direction than an MBT (Minimum angle for Best Torque) point, an ignition timing is set before a compression stroke top dead center in a no-load region of the engine, and the ignition timing is retarded after the compression top dead center in a low-speed-and-low-load region except the no-load region. The above-described later period injection is carried out after a middle period of the compression stroke, for example, 120° BTDC (Before Top Dead Center) through 45° BTDC.